The number of internally displaced, who frequently flee persecution but do not cross an international border, is greater than the number of refugees. Stateless persons, like refugees, often face deprivation of fundamental rights and require assistance from states of which they are not nationals. Environmentally induced migration is involuntary and in case of sudden events, like tsunamis or volcano eruptions, it may lead to precipitous large scale movements. Although traditional refugee law does not generally address these phenomena, all three of them have links to refugee movements and need to be addressed by those studying and assisting refugees.